Transmission apparatus, transmission method, reception apparatus, and reception method

ABSTRACT

To make high-level copyright protection of transmission audio data possible. Audio data is sequentially transmitted to a reception side via a predetermined transmission channel for each unit audio data. Audio data to be transmitted is encrypted, and encryption information indicating that the audio data has been encrypted is added to the audio data. For example, the encryption information is added using a predetermined bit area of a channel status of each block that is configured every predetermined number of unit audio data pieces.

TECHNICAL FIELD

The present invention relates to a transmission apparatus, atransmission method, a reception apparatus, and a reception method, moreparticularly, to a transmission apparatus that transmits audio data, andthe like.

BACKGROUND ART

For example, Patent Literature 1 includes descriptions on an IEC 60958standard. In this standard, an LPCM (Linear Pulse Code Modulation)transmission is limited to a maximum of two channels. Specifically,transmissions of two channels are defined in an IEC 60958-1 standard,and a linear PCM is allocated to each of the channels in an IEC 60958-3standard. It should be noted that a physical layer for a coaxial outputand optical output from an RCA pin terminal, and the like arestandardized in the IEC 60958-1 standard, and a physical layerequivalent to the coaxial output is standardized in HDMI ARC(High-Definition Multimedia Interface Audio Return Channel).

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Application Laid-open No.2009-130606

DISCLOSURE OF INVENTION Technical Problem

The IEC 60958 standard started off from a sampling frequency of 32 kHz,44.1 kHz, 48 kHz, and the like. High-quality sound audio transmissionshave become possible by later revision of the standard that involvesdefining sampling frequencies of a higher speed, such as 88.2 kHz, 96kHz, and 192 kHz and proposal of multichannel audio transmissions.

Therefore, a more robust copyright protection system is being required.However, currently applied is SCMS (Serial Copy Management System) thatonly indicates a copy management state. In addition, audio data itselfis transmitted in plain text, and the copy management state may beignored in a computer apparatus, with the result that data can be copiedand copyright protection is insufficient.

The present technology aims at making high-level copyright protection oftransmission audio data possible.

Solution to Problem

According to a concept of the present technology, there is provided atransmission apparatus including:

-   -   a data transmission unit that sequentially transmits audio data        to a reception side via a predetermined transmission channel for        each unit audio data;    -   an encryption unit that encrypts the audio data transmitted by        the data transmission unit; and    -   an information addition unit that adds, to the audio data        transmitted by the data transmission unit, encrypted-state        information indicating that the audio data has been encrypted.

In the present technology, the data transmission unit that sequentiallytransmits the audio data to the reception side via the predeterminedtransmission channel for each unit audio data. For example, the audiodata may be multichannel audio data of a predetermined number ofchannels, and the data transmission unit may sequentially transmit audiodata of the respective channels configuring the multichannel audio datato the reception side via the predetermined transmission channel foreach unit audio data. In this case, for example, the predeterminednumber of channels may be 6, 12, or 24.

The encryption unit encrypts the audio data transmitted by the datatransmission unit. Then, the information addition unit adds, to theaudio data transmitted by the data transmission unit, encrypted-stateinformation indicating that the audio data has been encrypted. Forexample, the information addition unit may add the encrypted-stateinformation using a predetermined bit area of a channel status of eachblock that is configured every predetermined number of unit audio datapieces.

In this case, for example, the information addition unit may indicatethe encrypted state by alternately and repetitively setting, for therespective blocks, “0” and “1” as a value of a predetermined 1-bit areaof the channel status of each block. The predetermined 1-bit area may bean area that indicates whether the audio data transmitted by the datatransmission unit is linear PCM.

As described above, in the present technology, the audio datatransmitted by the data transmission unit is encrypted, andencrypted-state information indicating that the audio data has beenencrypted is added to the audio data. Therefore, high-level copyrightprotection of transmission audio data becomes possible, and encryptionof audio data can be easily recognized on the reception side.

It should be noted that in the present technology, the informationaddition unit may further add, to the audio data transmitted by the datatransmission unit, encryption scheme information that indicates anencryption scheme for the encryption, for example. In this case, forexample, the information addition unit may add the encryption schemeinformation using a predetermined bit area of a channel status of eachblock that is configured every predetermined number of unit audio datapieces. By adding the encryption scheme information to the transmissionaudio data as described above, it becomes possible to easily recognizethe encryption scheme the audio data has been encrypted by on thereception side and appropriately carry out the decode processing.

According to another concept of the present technology, there isprovided a reception apparatus including:

-   -   a data reception unit that sequentially receives audio data        transmitted from a transmission side via a predetermined        transmission channel for each unit audio data,        -   the audio data received by the data reception unit being            encrypted,        -   the audio data received by the data reception unit having            encrypted-state information indicating that the audio data            has been encrypted added thereto; and    -   a decoding unit that carries out decode processing on the audio        data received by the data reception unit based on the        encrypted-state information.

In the present technology, the data reception unit sequentially receivesthe audio data from the transmission side via the predeterminedtransmission channel for each unit audio data. For example, the audiodata may be multichannel audio data of a predetermined number ofchannels, and the data reception unit may sequentially receive audiodata of the respective channels configuring the multichannel audio datafrom the transmission side via the predetermined transmission channelfor each unit audio data. In this case, for example, the predeterminednumber of channels may be 6, 12, or 24.

The audio data received by the data reception unit is encrypted.Further, encrypted-state information indicating that the audio data hasbeen encrypted is added to the audio data. The decoding unit carries outdecode processing on the audio data received by the data reception unitbased on the encrypted-state information. For example, theencrypted-state information may be added to the audio data received bythe data reception unit using a predetermined bit area of a channelstatus of each block that is configured every predetermined number ofunit audio data pieces.

In this case, the encrypted state may be indicated by alternately andrepetitively setting, for the respective blocks, “0” and “1” as a valueof a predetermined 1-bit area of the channel status of each block. Thepredetermined 1-bit area is originally an area that indicates whetherthe audio data received by the data reception unit is linear PCM and hasbeen changed when switching contents, and “0” and “1” have never beenrepeated for the respective blocks within a single content.

As described above, according to the present technology, the decodeprocessing is carried out on the reception audio data based on theencrypted-state information added to the audio data. Therefore, itbecomes possible to easily recognize that the reception audio data hasbeen encrypted and carry out the decode processing.

It should be noted that in the present technology, for example, theaudio data received by the data reception unit may further haveencryption scheme information that indicates an encryption scheme forthe encryption added thereto, and the decoding unit may carry out, onthe audio data received by the data reception unit, decode processingcorresponding to the encryption scheme indicated by the encryptionscheme information. In this case, for example, the encryption schemeinformation may be added to the audio data received by the datareception unit using a predetermined bit area of a channel status ofeach block that is configured every predetermined number of unit audiodata pieces. In this case, the decode processing can be carried outappropriately on the reception audio data.

Advantageous Effects of Invention

According to the present technology, high-level copyright protection oftransmission audio data becomes possible. It should be noted that theeffects described in the specification are mere examples and should notbe limited thereto, and additional effects may also be obtained.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] A block diagram showing a configuration example of an AV systemaccording to an embodiment.

[FIG. 2] A block diagram showing a configuration example of a televisionreceiver configuring the AV system.

[FIG. 3] A block diagram showing a configuration example of an audioamplifier configuring the AV system.

[FIG. 4] A block diagram showing a configuration example of a BD playerconfiguring the AV system.

[FIG. 5] A block diagram showing a configuration example of an HDMIreception unit of the television receiver and an HDMI transmission unitof the audio amplifier.

[FIG. 6] A diagram showing various transmission data sections in a casewhere image data having a horizontal*vertical size of 1920 pixels*1080lines is transmitted in a TMDS channel.

[FIG. 7] A diagram showing an HDMI connector pin arrangement.

[FIG. 8] A diagram showing a configuration example of a high-speed businterface of the television receiver.

[FIG. 9] A diagram showing a configuration example of a high-speed businterface of the audio amplifier.

[FIG. 10] A diagram showing a frame configuration in an IEC 60958standard.

[FIG. 11] A diagram showing a sub-frame configuration in the IEC 60958standard.

[FIG. 12] A diagram showing a signal modulation system in the IEC 60958standard.

[FIG. 13] A diagram showing channel coding of preambles in the IEC 60958standard.

[FIG. 14] A diagram schematically showing a channel status format in theIEC 60958 standard.

[FIG. 15] A diagram showing a current specified state of samplingfrequencies.

[FIG. 16] Diagrams showing a correspondence relationship between thenumber of channels and the sampling frequency in a case where thesampling frequency per channel is 48 kHz.

[FIG. 17] A diagram showing an example of a frame configuration in amultichannel transmission using 6 channels.

[FIG. 18] A diagram showing an example of values of “bit 67-74” in achannel status and a correspondence relationship between channelsrespectively indicated by those values and speaker positions.

[FIG. 19] Diagrams each showing an example of UI display on a receptionside.

[FIG. 20] Diagrams respectively showing configuration examples of anaudio short descriptor and a descriptor to be newly defined.

[FIG. 21] A flowchart showing an operational example of the televisionreceiver as an SPDIF signal transmission side.

[FIG. 22] Diagrams each showing an example of UI display when promptinga user to select a desired output mode.

[FIG. 23] A block diagram for specifically explaining encryption.

[FIG. 24] A diagram showing a state where “Byte0 Bit1” of the channelstatus is set to “0”.

[FIG. 25] A diagram showing a state where “Byte0 Bit1” of the channelstatus is set to “1”.

[FIG. 26] A sequence diagram for explaining operations on thetransmission side and reception side when transmitting SPDIF signals.

[FIG. 27] A diagram showing a transition of “Byte0 Bit1” whentransmitting SPDIF signals.

[FIG. 28] A diagram showing an example of preambles to be newly defined.

[FIG. 29] A diagram showing an example of a frame configuration in amultichannel transmission of 6 channels in a case where preambles to benewly defined are used as the preambles in place of preambles “B”, “M”,and “W”.

[FIG. 30] A diagram showing another example of a frame configuration inthe multichannel transmission of 6 channels in a case where preambles tobe newly defined are used.

[FIG. 31] A block diagram showing a configuration example of the AVsystem in a case where an optical cable is used as an IEC 60958transmission channel.

[FIG. 32] Diagrams respectively showing examples where an HDMItransmission channel and a display port transmission channel are used asthe EC 60958 transmission channel.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a mode for carrying out the invention (hereinafter,referred to as “embodiment”) will be described. It should be noted thatdescriptions will be given in the following order.

1. Embodiment 2. Modified Examples 1. Embodiment

[Configuration Example of AV system]

FIG. 1 shows a configuration example of an AV system 10 according to anembodiment. The AV system 10 includes a television receiver 100 as asink apparatus, an audio amplifier 200 as a repeater apparatus, and a BD(Blu-ray Disc) player 300 as a source apparatus. A television broadcastreception antenna 400 is connected to the television receiver 100 andthe BD player 300. Moreover, a 2-channel or multichannel speaker system500 is connected to the audio amplifier 200.

The television receiver 100 and the audio amplifier 200 are connected toeach other via an HDMI cable 610. Provided in the television receiver100 is an HDMI terminal 101 to which an HDMI reception unit (HDMI RX)102 and a high-speed bus interface 103 configuring a communication unitare connected. To the high-speed bus interface 103, an Ethernetinterface 115 and an SPDIF (Sony Philips Digital Interface) transmissioncircuit 104 are connected. The SPDIF transmission circuit 104 includesan encryption unit 104 a.

Further, an HDMI terminal 201 a to which an HDMI transmission unit (HDMITX) 202 a and a high-speed bus interface 203 a configuring acommunication unit are connected is provided in the audio amplifier 200.Connected to the high-speed bus interface 203 a are an Ethernetinterface 210 and an SPDIF reception circuit 204. The SPDIF receptioncircuit 204 includes a decoding unit 204 a. One end of the HDMI cable610 described above is connected to the HDMI terminal 101 of thetelevision receiver 100, and the other end of the HDMI cable 610 isconnected to the HDMI terminal 201 a of the audio amplifier 200.

Further, the audio amplifier 200 and the BD player 300 are connected toeach other via an HDMI cable 620. In the audio amplifier 200, an HDMIterminal 201 b to which an HDMI reception unit (HDMI RX) 202 b and ahigh-speed bus interface 203 b configuring the communication unit areconnected is provided.

Furthermore, in the BD player 300, an HDMI terminal 301 to which an HDMItransmission unit (HDNI TX) 302 and a high-speed bus interface 303configuring a communication unit are connected is provided. One end ofthe HDMI cable 620 described above is connected to the HDMI terminal 201b of the audio amplifier 200, and the other end of the HDMI cable 620 isconnected to the HDMI terminal 301 of the BD player 300.

[Configuration Example of Television Receiver]

FIG. 2 shows a configuration example of the television receiver 100. Thetelevision receiver 100 includes the HDMI terminal 101, the HDMIreception unit 102, the high-speed bus interface 103, and the SPDIF(Sony Philips Digital Interface) transmission circuit 104. Thetelevision receiver 100 also includes an antenna terminal 105, a digitaltuner 106, an MPEG decoder 107, a video signal processing circuit 108, agraphic generation circuit 109, a panel drive circuit 110, and a displaypanel 111.

The television receiver 100 also includes an audio signal processingcircuit 112, an audio amplification circuit 113, a speaker 114, theEthernet interface (Ethernet I/F) 115, and a network terminal 116. Thetelevision receiver 100 also includes an internal bus 120, a CPU 121, aflash ROM 122, an SDRAM (Synchronous RAM) 123, a display control unit124, a remote control reception unit 125, a remote control transmitter126, and a power supply unit 127. It should be noted that the “Ethernet”is a registered trademark.

The CPU 121 controls operations of the respective units of thetelevision receiver 100. The flash ROM 122 stores control software anddata. The SDRAM 123 configures a working area of the CPU 121. The CPU121 develops software and data read out from the flash ROM 122 in theSDRAM 123 and activates the software to control the respective units ofthe television receiver 100.

The remote control reception unit 125 receives a remote control signal(remote control code) transmitted from the remote control transmitter126 and supplies it to the CPU 121. The CPU 121 controls the respectiveunits of the television receiver 100 based on the remote control code.It should be noted that although a remote control unit is illustrated asa user instruction input unit in this embodiment, the user instructioninput unit may take other configurations, the examples of which includea touch panel unit to which an instruction is input by a proximity/touchoperation, a mouse, a keyboard, a gesture input unit that detects aninstruction input by a camera, and an audio input unit to which aninstruction is input by audio.

The antenna terminal 105 is a terminal for inputting televisionbroadcast signals received via a reception antenna (not shown). Thedigital tuner 106 processes the television broadcast signals input tothe antenna terminal 105 and extracts a partial TS (Transport Steam) (TSpacket of video data, TS packet of audio data) from a predeterminedtransport stream corresponding to a channel selected by a user.

The digital tuner 106 also takes out PSI/SI (Program SpecificInformation/Service Information) from the acquired transport stream andoutputs it to the CPU 121. Processing of extracting a partial TS of anarbitrary channel from a plurality of transport streams obtained by thedigital tuner 106 becomes possible by obtaining packet ID (PID)information of the arbitrary channel from PSI/SI (PAT/PMT).

The MPEG decoder 107 carries out decode processing on a video PES(Packetized Elementary Stream) packet constituted of TS packets of videodata obtained by the digital tuner 106 to obtain image data. The MPEGdecoder 107 also carries out decode processing on an audio PES packetconstituted of TS packets of audio data obtained by the digital tuner106 to obtain audio data.

The video signal processing circuit 108 and the graphic generationcircuit 109 carry out scaling processing (resolution conversionprocessing), graphics data superimposition processing, and the like onthe image data obtained by the MPEG decoder 107 or the image datareceived by the HDMI reception unit 102 as necessary.

The panel drive circuit 110 drives the display panel 111 based on thevideo (image) data output from the graphic generation circuit 109. Thedisplay control unit 124 controls the graphic generation circuit 109 andthe panel drive circuit 110 to control display of the display panel 111.The display panel 111 is constituted of, for example, an LCD (LiquidCrystal Display), a PDP (Plasma Display Panel), or an organic EL panel(Organic Electro-Luminescence Panel).

It should be noted that although the example where the display controlunit 124 is provided in addition to the CPU 121 is shown in thisembodiment, display on the display panel 111 may be directly controlledby the CPU 121. Moreover, the CPU 121 and the display control unit 124may be configured as one chip or as a plurality of cores. The powersupply unit 127 supplies power to the respective units of the televisionreceiver 100. The power supply unit 127 may be an AC power supply or abattery (storage battery, dry-cell battery).

The audio signal processing circuit 112 carries out requisite processingsuch as D/A conversion on the audio data obtained by the MPEG decoder107. The audio amplification circuit 113 amplifies audio signals outputfrom the audio signal processing circuit 112 and supplies the signals tothe speaker 114. It should be noted that the speaker 114 may either bemonaural or stereo. In addition, the number of speaker 114 may be one ortwo or more. Further, the speaker 114 may either be earphones or aheadphone. Moreover, the speaker 114 may be a speaker that supports 2.1channel, 5.1 channel, and the like. Furthermore, the speaker 114 may beconnected wirelessly to the television receiver 100. Further, thespeaker 114 may be other apparatuses.

The network terminal 116 is a terminal for connecting to a network andis connected to the Ethernet interface 115. The CPU 121, the flash ROM122, the SDRAM 123, the Ethernet interface 115, and the display controlunit 124 are connected to the internal bus 120.

The HDMI reception unit (HDMI sink) 102 receives a baseband image(video) and audio data supplied to the HDMI terminal 101 via the HDMIcable by communication conforming to HDMI. The high-speed bus interface103 is an interface for a bidirectional communication channel that isconfigured using a reserve line and an HPD line configuring the HDMIcable.

The SPDIF transmission circuit 104 is a circuit for transmitting digitalaudio transmission signals (hereinafter, referred to as “SPDIF signals”as appropriate) of the IEC 60958 standard. The SPDIF transmissioncircuit 104 is a transmission circuit conforming to the IEC 60958standard. In this embodiment, the SPDIF transmission circuit 104generates SPDIF signals including audio data of respective channelsusing 2-channel or multichannel audio data SA.

The audio data SA is 2-channel audio data, 5.1-channel audio data,7.1-channel audio data, 10.2-channel audio data, 22.2-channel audiodata, and the like obtained by the MPEG decoder 107, for example. Inthis embodiment, linear PCM audio data of the respective channelsincluded in the SPDIF signals generated by the SPDIF transmissioncircuit 104 is encrypted. The SPDIF signals and encryption will bedescribed later in detail.

The high-speed bus interface 103 is inserted between the Ethernetinterface 115 and the HDMI terminal 101. The high-speed bus interface103 supplies reception data received from a counterpart apparatus viathe HDMI cable and the HDMI terminal 101 to the CPU 121 via the Ethernetinterface 115.

The high-speed bus interface 103 also transmits transmission datasupplied from the CPU 121 via the Ethernet interface 115 to thecounterpart apparatus from the HDMI terminal 101 via the HDMI cable. Thehigh-speed bus interface 103 also transmits the SPDIF signals generatedby the SPDIF transmission circuit 104 to the counterpart apparatus fromthe HDMI terminal 101 via the HDMI cable.

It should be noted that when transmitting received content data to anetwork, for example, the content data is output to the network terminal116 via the Ethernet interface 115. Similarly, when transmittingreceived content data to a bidirectional communication channel of theHDMI cable, the content data is output to the HDMI terminal 101 via theEthernet interface 115 and the high-speed bus interface 103. Here, acopyright protection technology such as HDCP, DTCP, and DTCP+ may beused for the encryption before outputting image data.

An operation of the television receiver 100 shown in FIG. 2 will simplybe described. Television broadcast signals input to the antenna terminal105 are supplied to the digital tuner 106. In the digital tuner 106, thetelevision broadcast signals are processed, a predetermined transportstream corresponding to a user-selected channel is output, partial TSs(TS packets of video data, TS packets of audio data) are extracted, andthe partial TSs are supplied to the MPEG decoder 107.

In the MPEG decoder 107, decode processing is carried out on a video PESpacket constituted of TS packets of video data to obtain video data. Thevideo data is subjected to scaling processing (resolution conversionprocessing), graphics data superimposition processing, and the like asnecessary in the video signal processing circuit 108 and the graphicgeneration circuit 109 and then supplied to the panel drive circuit 110.Therefore, an image corresponding to the user-selected channel isdisplayed on the display panel 111.

Also in the MPEG decoder 107, decode processing is carried out on anaudio PES packet constituted of TS packets of audio data to obtain audiodata. The audio data is subjected to requisite processing such as D/Aconversion by the audio signal processing circuit 112, amplified by theaudio amplification circuit 113, and then supplied to the speaker 114.Therefore, audio corresponding to the user-selected channel is outputfrom the speaker 114.

Further, content data (image data, audio data) supplied to the Ethernetinterface 115 from the network terminal 116 or supplied from the HDMIterminal 101 to the Ethernet interface 115 via the high-speed businterface 103 is supplied to the MPEG decoder 107. Operations after thatare operations similar to those described above that are carried outwhen receiving television broadcast signals, and thus an image isdisplayed on the display panel 111 and audio is output from the speaker114.

Further, the HDMI reception unit 102 acquires image data and audio datatransmitted to the HDMI terminal 101 via the HDMI cable. The image datais supplied to the video signal processing circuit 108, and the audiodata is supplied to the audio signal processing circuit 112. Operationsafter that are operations similar to those described above that arecarried out when receiving television broadcast signals, and thus animage is displayed on the display panel 111 and audio is output from thespeaker 114.

Further, SPDIF signals that are generated by the SPDIF transmissioncircuit 104 and include audio data of the respective channels of 2channels or multi-channels are supplied to the high-speed bus interface103. Then, by the high-speed bus interface 103, the SPDIF signals aretransmitted from the HDMI terminal 101 to the audio amplifier 200 viathe HDMI cable 610.

[Configuration Example of Audio Amplifier]

FIG. 3 shows a configuration example of the audio amplifier 200. Theaudio amplifier 200 includes the HDMI terminals 201 a and 201 b, theHDMI transmission unit 202 a, the HDMI reception unit 202 b, thehigh-speed bus interfaces 203 a and 203 b, and the SPDIF receptioncircuit 204.

The audio amplifier 200 also includes an MPEG decoder 205, avideo/graphic processing circuit 206, an audio processing circuit 207,an audio amplification circuit 208, and an audio output terminal 209.The audio amplifier 200 also includes the Ethernet interface 210, aninternal bus 211, a CPU 212, a flash ROM 213, a DRAM 214, a displaycontrol unit 215, a panel drive circuit 216, a display panel 217, apower supply unit 218, a remote control reception unit 219, and a remotecontrol transmitter 220.

The CPU 212 controls operations of the respective units of the audioamplifier 200. The flash ROM 213 stores control software and data. TheDRAM 214 configures a working area of the CPU 212. The CPU 212 developssoftware and data read out from the flash ROM 213 in the DRAM 214 andactivates the software to control the respective units of the audioamplifier 200. The CPU 212, the flash ROM 213, the DRAM 214, theEthernet interface 210, and the display control unit 215 are connectedto the internal bus 211.

The remote control reception unit 219 receives a remote control signal(remote control code) transmitted from the remote control transmitter220 and supplies it to the CPU 212. The CPU 212 controls the respectiveunits of the audio amplifier 200 based on the remote control code. Itshould be noted that although a remote control unit is illustrated asthe user instruction input unit in this embodiment, the user instructioninput unit may take other configurations, the examples of which includea touch panel unit to which an instruction is input by a proximity/touchoperation, a mouse, a keyboard, a gesture input unit that detects aninstruction input by a camera, and an audio input unit to which aninstruction is input by audio.

The HDMI transmission unit (HDMI source) 202 a transmits a basebandvideo (image) and audio data to the HDMI cable from the HDMI terminal201 a by communication conforming to HDMI. The HDMI reception unit (HDMIsink) 202 b receives the baseband video (image) and audio data suppliedto the HDMI terminal 201 b via the HDMI cable by communicationconforming to HDMI. The HDMI transmission unit 202 a and the HDMIreception unit 202 b will be described later in detail.

The high-speed bus interfaces 203 a and 203 b are each an interface forbidirectional communication that uses a reserve line and an HPD lineconfiguring the HDMI cable. The high-speed bus interfaces 203 a and 203b will be described later in detail. The SPDIF reception circuit 204 isa circuit for receiving SPDIF signals (digital audio transmissionsignals of IEC 60958 standard). The SPDIF reception circuit 204 is areception circuit conforming to the IEC 60958 standard.

In this embodiment, the SPDIF reception circuit 204 receives SPDIFsignals including audio data of the respective channels of 2 channels ormulti-channels and outputs audio data of the respective channels. Here,linear PCM audio data of the respective channels included in the SPDIFsignals is encrypted. Therefore, the SPDIF reception circuit 204 carriesout decode processing on the linear PCM audio data of the respectivechannels to obtain the audio data of the respective channels.

The MPEG decoder 205 decodes partial TSs supplied to the Ethernetinterface 210 via the high-speed bus interface 203 a. In this case, thedecode processing is carried out on an audio PES packet out of thepartial TSs to obtain audio data.

The audio processing circuit 207 carries out requisite processing suchas D/A conversion on the 2-channel or multichannel audio data that hasbeen obtained by the MPEG decoder 205 or received by the SPDIF receptioncircuit 204. The audio amplification circuit 208 amplifies the 2-channelor multichannel audio signals obtained by the audio processing circuit207 and outputs the signals to the audio output terminal 209. It shouldbe noted that the 2-channel or multichannel speaker system 500 isconnected to the audio output terminal 209.

The audio processing circuit 207 further carries out requisiteprocessing on the audio data obtained by the HDMI reception unit 202 band then supplies the data to the HDMI transmission unit 202 a. Thevideo/graphic processing circuit 206 carries out graphics datasuperimposition processing and the like on the video (image) dataobtained by the HDMI reception unit 202 b and then supplies the data tothe HDMI transmission unit 202 a.

The display control unit 215 controls the panel drive circuit 216 forperforming user interface display, status display of the audio amplifier200, and the like and controls display of the display panel 217. Thedisplay panel 217 is constituted of, for example, an LCD (Liquid CrystalDisplay) or an organic EL panel (Organic Electro-Luminescence Panel).

It should be noted that although the example where the display controlunit 215 is provided in addition to the CPU 212 is shown in thisembodiment, display on the display panel 217 may be directly controlledby the CPU 212. Moreover, the CPU 212 and the display control unit 215may be configured as one chip or as a plurality of cores. The powersupply unit 218 supplies power to the respective units of the audioamplifier 200. The power supply unit 218 may be an AC power supply or abattery (storage battery, dry-cell battery).

An operation of the audio amplifier 200 shown in FIG. 3 will simply bedescribed. The HDMI reception unit 202 b receives the video (image) dataand audio data transmitted from the BD player 300 to the HDMI terminal201 b via the HDMI cable 620. This video data and audio data aresupplied to the HDMI transmission unit 202 a via the video/graphicprocessing circuit 206 and the audio processing circuit 207 andtransmitted to the television receiver 100 via the HDMI cable 610connected to the HDMI transmission unit 202 a.

The high-speed bus interface 203 a receives partial TSs transmitted fromthe television receiver 100 via a predetermined line of the HDMI cable610 connected to the HDMI terminal 201 a. The partial TSs are suppliedto the MPEG decoder 205 via the Ethernet interface 211. In the MPEGdecoder 205, decode processing is carried out on a PES packet of audiodata constituting the partial TS to obtain 2-channel or multichannelaudio data.

This audio data is supplied to the audio processing circuit 207 to besubjected to requisite processing such as D/A conversion. Then, whenmuting is off, the audio signals of the respective channels output fromthe audio processing circuit 207 are amplified and output to the audiooutput terminal 209. Therefore, 2-channel or multichannel audio isoutput from the speaker system 500.

The high-speed bus interface 203 a also receives SPDIF signals includingthe 2-channel or multichannel audio data, that are transmitted from thetelevision receiver 100 via a predetermined line of the HDMI cable 610connected to the HDMI terminal 201 a. The SPDIF signals are supplied tothe SPDIF reception circuit 204. The SPDIF reception circuit 204processes the SPDIF signals so as to obtain the 2-channel ormultichannel audio data.

This audio data is supplied to the audio processing circuit 207 to besubjected to requisite processing such as D/A conversion. Then, whenmuting is off, the audio signals of the respective channels output fromthe audio processing circuit 207 are amplified and output to the audiooutput terminal 209. Therefore, 2-channel or multichannel audio isoutput from the speaker system 500.

It should be noted that the partial TSs received by the high-speed businterface 203 a and supplied to the Ethernet interface 210 as describedabove are supplied to the high-speed bus interface 203 b as transmissiondata. Therefore, the partial TSs are transmitted to the BD player 300via the HDMI cable 620 connected to the HDMI terminal 201 b.

[Configuration Example of BD Player]

FIG. 4 shows a configuration example of the BD player 300. The BD player300 includes the HDMI terminal 301, the HDMI transmission unit 302, andthe high-speed bus interface 303. The BD player 300 also includes aninternal bus 304, a CPU (Central Processing Unit) 305, a flash ROM (ReadOnly Memory) 306, an SDRAM (Synchronous Random Access Memory) 307, adisplay control unit 308, a remote control reception unit 309, and aremote control transmitter 310.

The BD player 300 also includes a storage (recording) medium controlinterface 311, a BD (Blu-ray Disc) drive 312 a, an HDD (Hard disk drive)312 b, an SSD (Solid State Drive) 312 c, an Ethernet interface (EthernetI/F) 313, and a network terminal 314. The BD player 300 also includes anMPEG (Moving Picture Expert Group) decoder 315, a graphic generationcircuit 316, a video output terminal 317, and an audio output terminal318.

The BD player 300 also includes a panel drive circuit 319, a displaypanel 320, and a power supply unit 321. The CPU 305, the flash ROM 306,the SDRAM 307, the storage medium control interface 311, the Ethernetinterface 313, and the MPEG decoder 315 are connected to the internalbus 304.

The CPU 305 controls operations of the respective units of the BD player300. The flash ROM 306 stores control software and data. The SDRAM 307configures a working area of the CPU 305. The CPU 305 develops softwareand data read out from the flash ROM 306 in the SDRAM 307 and activatesthe software to control the respective units of the BD player 300.

The remote control reception unit 309 receives a remote control signal(remote control code) transmitted from the remote control transmitter310 and supplies it to the CPU 305. The CPU 305 controls the respectiveunits of the BD player 300 based on the remote control code. It shouldbe noted that although a remote control unit is illustrated as the userinstruction input unit in this embodiment, the user instruction inputunit may take other configurations, the examples of which include aswitch, a wheel, a touch panel unit to which an instruction is input bya proximity/touch operation, a mouse, a keyboard, a gesture input unitthat detects an instruction input by a camera, and an audio input unitto which an instruction is input by audio.

The BD drive 312 a records and reproduces content data to/from a BD discas a disc-type recording medium. The HDD 312 b records and reproducescontent data. The SSD 312 c records and reproduces content data to/froma semiconductor memory such as a memory card.

The BD drive 312 a, the HDD 312 b, and the SSD 312 c are connected tothe internal bus 304 via the storage medium control interface 311. Forexample, a SATA interface is used as interfaces for the BD drive 312 aand the HDD 312 b. Further, for example, a SATA interface or a PCIeinterface is used as an interface for the SSD 312 c.

The MPEG decoder 315 carries out decode processing on an MPEG2 streamreproduced by the BD drive 312 a, the HDD 312 b, or the SSD 312 c toobtain image and audio data. The graphic generation circuit 316 carriesout graphics data superimposition processing and the like on the imagedata obtained by the MPEG decoder 315 as necessary. The video outputterminal 317 outputs the image data output from the graphic generationcircuit 316. The audio output terminal 318 outputs the audio dataobtained by the MPEG decoder 315.

The panel drive circuit 319 drives the display panel 320 based on thevideo (image) data output from the graphic generation circuit 316. Thedisplay control unit 308 controls the graphic generation circuit 316 andthe panel drive circuit 319 to control display on the display panel 320.The display panel 320 is constituted of, for example, an LCD (LiquidCrystal Display), a PDP (Plasma Display Panel), or an organic EL panel(Organic Electro-Luminescence Panel).

It should be noted that although the example where the display controlunit 308 is provided in addition to the CPU 305 is shown in thisembodiment, display on the display panel 320 may be directly controlledby the CPU 305. Moreover, the CPU 305 and the display control unit 308may be configured as one chip or as a plurality of cores. The powersupply unit 321 supplies power to the respective units of the BD player300. The power supply unit 321 may be an AC power supply or a battery(storage battery, dry-cell battery).

The HDMI transmission unit (HDMI source) 302 transmits a baseband image(video) and audio data from the HDMI terminal 301 by communicationconforming to HDMI. The high-speed bus interface 303 is an interface fora bidirectional communication channel that is configured using a reserveline and an HPD line configuring the HDMI cable.

The high-speed bus interface 303 is inserted between the Ethernetinterface 313 and the HDMI terminal 301. The high-speed bus interface303 transmits transmission data supplied from the CPU 305 to thecounterpart apparatus from the HDMI terminal 301 via the HDMI cable. Thehigh-speed bus interface 303 also supplies reception data received fromthe counterpart apparatus via the HDMI cable and the HDMI terminal 301to the CPU 305.

An operation of the BD player 300 shown in FIG. 4 will simply bedescribed. At the time of recording, content data to be recorded isacquired via a digital tuner (not shown), from the network terminal 314via the Ethernet interface 311, or from the HDMI terminal 301 via thehigh-speed bus interface 303. The content data is input to the storagemedium control interface 311 and recorded onto a BD disc by the BD drive312 a, the HDD 312 b, or a semiconductor memory by the SSD 312 c.

At the time of reproduction, content data (MPEG stream) reproduced bythe BD drive 312 a, the HDD 312 b, or the SSD 312 c is supplied to theMPEG decoder 315 via the storage medium control interface 311. The MPEGdecoder 315 carries out decode processing on the reproduced content datato obtain baseband image and audio data. The image data is output to thevideo output terminal 317 via the graphic generation circuit 316.Further, the audio data is output to the audio output terminal 318.

Further, the image data obtained by the MPEG decoder 315 is supplied tothe panel drive circuit 319 via the graphic generation circuit 316according to a user operation, and a reproduction image is displayed onthe display panel 320. Moreover, the audio data obtained by the MPEGdecoder 315 is supplied to a speaker (not shown) according to a useroperation so that audio corresponding to the reproduction image isoutput.

Furthermore, when transmitting the image and audio data obtained by theMPEG decoder 315 using an HDMI TMDS channel during reproduction, theimage and audio data is supplied to the HDMI transmission unit 302 to bepackaged, and then output to the HDMI terminal 301 from the HDMItransmission unit 302.

Also when transmitting content data reproduced by the BD drive 312 a,the HDD 312 b, or the SSD 312 c to a network during reproduction, thecontent data is output to the network terminal 314 via the Ethernetinterface 313. Similarly, when transmitting content data reproduced bythe BD drive 312 a, the HDD 312 b, or the SSD 312 c to a bidirectionalcommunication channel of the HDMI cable 620 during reproduction, thecontent data is output to the HDMI terminal 301 via the high-speed businterface 303. Here, a copyright protection technology such as HDCP,DTCP, and DTCP+ may be used for the encryption before outputting imagedata.

[Configuration Example of HDMI Transmission Unit/Reception unit]

FIG. 5 shows a configuration example of the HDMI reception unit 102 ofthe television receiver 100 and the HDMI transmission unit 202 a of theaudio amplifier 200 in the AV system 10 shown in FIG. 1. It should benoted that since configuration examples of the HDMI reception unit 202 bof the audio amplifier 200 and the HDMI transmission unit 302 of the BDplayer 300 are similar to those described above, descriptions thereofwill be omitted.

The HDMI transmission unit 202 a unidirectionally transmits baseband(uncompressed) differential signals of image data for one screen to theHDMI reception unit 102 by a plurality of channels in an effective imagesection (hereinafter, referred to as “active video section” asappropriate) as a section obtained by removing a horizontal blankingperiod and a vertical blanking period from a section between a certainvertical synchronization signal and the next vertical synchronizationsignal (hereinafter, referred to as “video field” as appropriate). TheHDMI transmission unit 202 a also unidirectionally transmits, in thehorizontal blanking period and the vertical blanking period,differential signals corresponding to audio data and a control packet(Control Packet) accompanying image data, other auxiliary data, and thelike to the HDMI reception unit 102 by the plurality of channels.

The HDMI transmission unit 202 a includes a source signal processingunit 71 and an HDMI transmitter 72. Uncompressed baseband image (Video)and audio (Audio) data are supplied to the source signal processing unit71. The source signal processing unit 71 carries out requisiteprocessing on the supplied image and audio data and supplies the data tothe HDMI transmitter 72. The source signal processing unit 71 alsoexchanges control information, information for notifying a status(Control/Status), and the like with the HDMI transmitter 72 asnecessary.

The HDMI transmitter 72 converts the image data supplied from the sourcesignal processing unit 71 into corresponding differential signals andunidirectionally transmits the signals to the HDMI reception unit 102connected via the HDMI cable 610 using 3 TMDS channels #0, #1, and #2 asthe plurality of channels.

The HDMI transmitter 72 also converts the audio data and control packet(Control Packet) accompanying the uncompressed image data and otherauxiliary data (auxiliary data) that are supplied from the source signalprocessing unit 71 and control data (control data) of the verticalsynchronization signal (VSYNC), the horizontal synchronization signal(HSYNC), and the like into corresponding differential signals, andunidirectionally transmits the signals to the HDMI reception unit 102connected via the HDMI cable 610 using the 3 TMDS channels #0, #1, and#2.

The HDMI transmitter 72 also transmits pixel clocks synchronized withthe image data to be transmitted by the 3 TMDS channels #0, #1, and #2to the HDMI reception unit 102 connected via the HDMI cable 610 by aTMDS clock channel.

The HDMI reception unit 102 receives the differential signalscorresponding to the image data that are unidirectionally transmittedfrom the HDMI transmission unit 202 a by the plurality of channels inthe active video section and receives the differential signalscorresponding to the auxiliary data and control data that aretransmitted from the HDMI transmission unit 202 a by the plurality ofchannels in the horizontal blanking period and the vertical blankingperiod.

The HDMI reception unit 102 includes an HDMI receiver 81 and asynchronization signal processing unit 82. The HDMI receiver 81synchronizes the differential signals corresponding to the image dataand the differential signals corresponding to the auxiliary data andcontrol data, that are unidirectionally transmitted from the HDMItransmission unit 202 a connected via the HDMI cable 610 using the TMDSchannels #0, #1, and #2, with the pixel clocks also transmitted from theHDMI transmission unit 202 a using the TMDS clock channel and receivesthe signals. The HDMI receiver 81 also converts the differential signalsinto corresponding image data, auxiliary data, and control data andsupplies the data to the synchronization signal processing unit 82 asnecessary.

The synchronization signal processing unit 82 carries out requisiteprocessing on the data supplied from the HDMI receiver 81 and outputsit. In addition, the synchronization signal processing unit 82 exchangescontrol information, information for notifying a status(Control/Status), and the like with the HDMI receiver 81 as necessary.

As the HDMI transmission channel, there are transmission channels calledDDC (Display Data Channel) 83 and CEC line 84 in addition to the 3 TMDSchannels #0, #1, and #2 for synchronizing image data, auxiliary data,and control data with pixel clocks and performing unidirectional serialtransmission from the HDMI transmission unit 202 a to the HDMI receptionunit 102 and the TMDS clock channel as a transmission channel fortransmitting pixel clocks.

The DDC 83 is constituted of two lines (signal lines) (not shown) thatare included in the HDMI cable 610 and is used for the source apparatusto read out E-EDID (Enhanced-Extended Display Identification) from thesink apparatus connected via the HDMI cable 610. In other words, thesink apparatus includes an EDIDROM 85. The source apparatus reads out,from the sink apparatus connected via the HDMI cable 610, E-EDID storedin the EDIDROM 85 via the DDC 83 and recognizes settings and performanceof the sink apparatus based on that E-EDID.

The CEC line 84 is constituted of one line (not shown) included in theHDMI cable 610 and is used for performing bidirectional communication ofcontrol data between the source apparatus and the sink apparatus.

The HDMI cable 610 also includes a line 86 connected to a pin called HPD(Hot Plug Detect). The source apparatus is capable of detecting aconnection with the sink apparatus using the line 86. The HDMI cable 610also includes a line 87 used for supplying power from the sourceapparatus to the sink apparatus. The HDMI cable 610 also includes areserve line 88.

FIG. 6 shows various transmission data sections in a case where imagedata having a horizontal*vertical size of 1920 pixels*1080 lines istransmitted in the TMDS channel. In a video field (Video Field) in whichtransmission data is transmitted by 3 TMDS channels of HDMI, there exist3 types of sections which are a video data section 24 (Video DataPeriod), a data island section 25 (Data Island Period), and a controlsection 26 (Control Period) according to the type of transmission data.

Here, the video field section is a section between a rising edge of acertain vertical synchronization signal (Active Edge) and a rising edgeof the next vertical synchronization signal and is sectioned into ahorizontal flyback period 22 (Horizontal Blanking), a vertical flybackperiod 23 (Vertical Blanking), and an effective pixel section 21 (ActiveVideo) as a section obtained by removing the horizontal flyback periodand the vertical flyback period from the video field section.

The video data section 24 is allocated to the effective pixel section21. In the video data section 24, data having effective pixels (ActivePixel) of 1920 pixels*1080 lines, that configure uncompressed image datafor one screen, is transmitted. The data island section 25 and thecontrol section 26 are allocated to the horizontal flyback period 22 andthe vertical flyback period 23. In the data island section 25 and thecontrol section 26, auxiliary data (Auxiliary Data) is transmitted.

Specifically, the data island section 25 is allocated to parts of thehorizontal flyback period 22 and the vertical flyback period 23. In thedata island section 25, a packet of audio data and the like as dataunrelated to control, for example, is transmitted out of auxiliary data.The control section 26 is allocated to other parts of the horizontalflyback period 22 and the vertical flyback period 23. In the controlsection 26, a vertical synchronization signal, a horizontalsynchronization signal, a control packet, and the like as data relatedto control, for example, are transmitted out of auxiliary data.

FIG. 7 shows an HDMI connector pin arrangement. This pin arrangement isan example of Type A (type-A). Two lines that are differential linesthrough which TMDS Data#i+ and TMDS Data#i− as differential signals ofTMDS channel #i are transmitted are connected to pins to which TMDSData#i+ is allocated (pins of pin numbers 1, 4, and 7) and pins to whichTMDS Data#i− is allocated (pins of pin numbers 3, 6, and 9).

Further, the CEC line 84 through which CEC signals as control data aretransmitted is connected to a pin having a pin number 13, and a pinhaving a pin number 14 is a reserved (Reserved) pin. Moreover, the linethrough which SDA (Serial Data) signals of E-EDID and the like aretransmitted is connected to a pin having a pin number 16, and the linethrough which SCL (Serial Clock) signals as clock signals used forsynchronization when transmitting and receiving SDA signals is connectedto a pin having a pin number 15. The DDC 83 described above isconfigured by the line through which SDA signals are transmitted and theline through which SCL signals are transmitted.

Further, the HPD line 86 used for the source apparatus to detect aconnection with the sink apparatus as described above is connected to apin having a pin number 19. Furthermore, the power supply line 87 forsupplying power as described above is connected to a pin having a pinnumber 18.

[Configuration Example of High-Speed Bus Interface]

FIG. 8 shows a configuration example of the high-speed bus interface 103of the television receiver 100 in the AV system 10. Of the plurality oflines configuring the HDMI cable 610, the Ethernet interface 115performs LAN (Local Area Network) communication, that is, exchangesEthernet signals, using a transmission channel constituted of a pair oflines including the reserve line and the HPD line. The SPDIFtransmission circuit 104 transmits SPDIF signals using the transmissionchannel constituted of the pair of lines described above.

The television receiver 100 includes a LAN signal transmission circuit441, a termination resistor 442, AC coupling capacitors 443 and 444, aLAN signal reception circuit 445, a subtraction circuit 446, additioncircuits 449 and 450, and an amplifier 451, which configure thehigh-speed bus interface 103. The television receiver 100 includes achoke coil 461 and resistors 462 and 463, which configure a plugconnection transmission circuit 128.

A series circuit of the AC coupling capacitor 443, the terminationresistor 442, and the AC coupling capacitor 444 is connected between a14 pin terminal 521 and 19 pin terminal 522 of the HDMI terminal 101.Further, a series circuit of the resistors 462 and 463 is connectedbetween the power supply wire (+5.0 V) and a grounding wire. Inaddition, a connection point between the resistors 462 and 463 isconnected to a connection point Q4 between the 19 pin terminal 522 andthe AC coupling capacitor 444 via the choke coil 461.

A connection point P3 between the AC coupling capacitor 443 and thetermination resistor 442 is connected to an output side of the additioncircuit 449 and also to a positive input side of the LAN signalreception circuit 445. In addition, a connection point P4 between the ACcoupling capacitor 444 and the termination resistor 442 is connected toan output side of the addition circuit 450 and also to a negative inputside of the LAN signal reception circuit 445.

One of input sides of the addition circuit 449 is connected to apositive output side of the LAN signal transmission circuit 441, andSPDIF signals output from the SPDIF transmission circuit 104 aresupplied to the other one of the input sides of the addition circuit 449via the amplifier 451. Further, one of input sides of the additioncircuit 450 is connected to a negative output side of the LAN signaltransmission circuit 441, and SPDIF signals output from the SPDIFtransmission circuit 104 are supplied to the other one of the inputsides of the addition circuit 450 via the amplifier 451.

A transmission signal (transmission data) SG417 is supplied from theEthernet interface 115 to the input side of the LAN signal transmissioncircuit 441. Further, an output signal SG418 of the LAN signal receptioncircuit 445 is supplied to a positive-side terminal of the subtractioncircuit 446, and the transmission signal SG417 is supplied to anegative-side terminal of the subtraction circuit 446. In thesubtraction circuit 446, the transmission signal SG417 is subtractedfrom the output signal SG418 of the LAN signal reception circuit 445, toobtain a reception signal (reception data) SG419. When a LAN signal(Ethernet signal) is transmitted as a differential signal via thereserve line and the HPD line, the reception signal SG419 becomes theLAN signal. The reception signal SG419 is supplied to the Ethernetinterface 115.

FIG. 9 shows a configuration example of the high-speed bus interface 203a of the audio amplifier 200 in the AV system 10 shown in FIG. 1. Of theplurality of lines configuring the HDMI cable 610, the Ethernetinterface 210 performs LAN (Local Area Network) communication, that is,exchanges Ethernet signals, using a transmission channel constituted ofa pair of lines including the reserve line and the HPD line. The SPDIFreception circuit 204 receives SPDIF signals using the transmissionchannel constituted of the pair of lines described above.

The audio amplifier 200 includes a LAN signal transmission circuit 411,a termination resistor 412, AC coupling capacitors 413 and 414, a LANsignal reception circuit 415, a subtraction circuit 416, an additioncircuit 419, and an amplifier 420, which configure the high-speed businterface 203 a. The audio amplifier 200 also includes a pulldownresistor 431, a resistor 432, a capacitor 433, and a comparator 434,which configure a plug connection detection circuit 221. Here, theresistor 432 and the capacitor 433 configure a low-pass filter.

A series circuit of the AC coupling capacitor 413, the terminationresistor 412, and the AC coupling capacitor 414 is connected between a14 pin terminal 511 and 19 pin terminal 512 of the HDMI terminal 201 a.Further, a connection point P1 between the AC coupling capacitor 413 andthe termination resistor 412 is connected to a positive output side ofthe LAN signal transmission circuit 411 and also to a positive inputside of the LAN signal reception circuit 415.

A connection point P2 between the AC coupling capacitor 414 and thetermination resistor 412 is connected to a negative output side of theLAN signal transmission circuit 411 and also to a negative input side ofthe LAN signal reception circuit 415. A transmission signal(transmission data) SG411 is supplied from the Ethernet interface 210 tothe input side of the LAN signal transmission circuit 411.

An output signal SG412 of the LAN signal reception circuit 415 issupplied to a positive-side terminal of the subtraction circuit 416, anda transmission signal (transmission data) SG411 is supplied to anegative-side terminal of the subtraction circuit 416. In thesubtraction circuit 416, the transmission signal SG411 is subtractedfrom the output signal SG412 of the LAN signal reception circuit 415, toobtain a reception signal SG413. When a LAN signal (Ethernet signal) istransmitted as a differential signal via the reserve line and the HPDline, the reception signal SG413 becomes the LAN signal. The receptionsignal SG413 is supplied to the Ethernet interface 210.

A connection point Q2 between the AC coupling capacitor 414 and the 19pin 512 is connected to a grounding wire via the pulldown resistor 431and also connected to the grounding wire via a series circuit of theresistor 432 and the capacitor 433. In addition, an output signal of thelow-pass filter that is obtained at the connection point between theresistor 432 and the capacitor 433 is supplied to one of input terminalsof the comparator 434. In the comparator 434, the output signal of thelow-pass filter is compared with a reference voltage Vref2 (+1.4 V)supplied to the other one of the input terminals. The output signalSG415 of the comparator 434 is supplied to a controller (CPU) (notshown) of the audio amplifier 200.

Further, a connection point P1 between the AC coupling capacitor 413 andthe termination resistor 412 is connected to one of input terminals ofthe addition circuit 419. Further, a connection point P2 between the ACcoupling capacitor 414 and the termination resistor 412 is connected tothe other one of the input terminals of the addition circuit 419. Theoutput signal of the addition circuit 419 is supplied to the SPDIFreception circuit 115 via the amplifier 420. When an SPDIF signal istransmitted as an in-phase signal via the reserve line and the HPD line,the output signal of the addition circuit 419 becomes the SPDIF signal.

It should be noted that although specific descriptions will be omitted,the high-speed bus interface 203 b of the audio amplifier 200 has aconfiguration similar to that obtained by removing a portion related toSPDIF signals from the high-speed bus interface 103 shown in FIG. 8.Moreover, although specific descriptions will be omitted, the high-speedbus interface 303 of the BD player 300 has a configuration similar tothat obtained by removing a portion related to SPDIF signals from thehigh-speed bus interface 203 a shown in FIG. 9.

[Details of SPDIF Signals]

First, a general outline of the IEC 60958 standard will be described.FIG. 10 shows a frame configuration in the IEC 60958 standard. Eachframe is constituted of two sub-frames. In the case of 2-channel stereoaudio, a left channel signal is included in the first sub-frame, and aright channel signal is included in the second sub-frame.

As will be described later, a preamble is provided at a head of asub-frame. “M” is assigned to the left channel signal as the preamble,and “W” is assigned to the right channel signal as the preamble. Itshould be noted that “B” that indicates a start of a block is assignedto the preamble at the head of every 192 frames. In other words, 1 blockis constituted of 192 frames. The block is a unit configuring a channelstatus to be described later.

FIG. 11 shows a sub-frame configuration in the IEC 60958 standard. Thesub-frame is constituted of 0 to 31st time slots, that is, a total of 32time slots. The 0 to 3rd time slots indicate a preamble (Sync Preamble).This preamble shows one of “M”, “W”, and “B” for distinguishing left andright channels from each other or expressing a block start position asdescribed above.

The 4th to 27th time slots are a main data field and the entire timeslots express audio data in a case where a 24-bit code range is adopted.Moreover, 8th to 27th time slots express audio data (Audio sample word)in a case where a 20-bit code range is adopted. In the latter case, the4th to 7th time slots can be used as additional information (Auxiliarysample bits).

A 28th time slot is a validity flag (Validity Flag) of the main datafield. A 29th time slot expresses 1 bit of user data (User data). Aseries of user data can be configured by accumulating this 29th slotacross frames. A message of this user data is configured with an 8-bitinformation unit (IU: Information Unit) being a unit, and one messageincludes 3 to 129 information units.

0- to 8-bit “0” may exist among the information units. The head of theinformation unit is identified by a start bit “1”. The first 7information units within the message is reserved, and a user can setarbitrary information in 8th and subsequent information units. Aninterval between messages is divided by “0” of 8 bits or more.

A 30th time slot expresses 1 bit of a channel status (Channel status). Aserial channel status can be configured by accumulating this 30th slotfor each block across frames. It should be noted that the head positionof a block is indicated by the preamble “B” (0 to 3rd time slots) asdescribed above.

A 31st time slot is a parity bit (Parity bit). This parity bit isassigned so that the number of “0” and “1” included in the 4th to 31sttime slots becomes an even number.

FIG. 12 shows a signal modulation system in the IEC 60958 standard. The4th to 31st time slots excluding the preamble out of the sub-frame aresubjected to biphase mark modulation. Clocks that are twice as fast asthe original signals (source coding) are used for the biphase markmodulation. When the clock cycle of the original signals is split intothe first half and the latter half, the biphase mark modulation outputis always inverted at edges of the first-half clock cycle. Moreover, atedges of the latter-half clock cycle, the output is inverted when theoriginal signals indicate “1” and is not inverted when the originalsignals indicate “0”. Accordingly, clock components in the originalsignals can be extracted from the signals subjected to the biphase markmodulation.

FIG. 13 shows channel coding of the preambles in the IEC 60958 standard.As described above, the 4th to 31st time slots of the sub-frame aresubjected to the biphase mark modulation. On the other hand, thepreamble of 0 to 3rd time slots is handled as a bit pattern in sync withthe double-speed clocks without being subjected to the normal biphasemark modulation. Specifically, by allocating 2 bits to each of the 0 to3rd time slots, an 8-bit pattern as shown in the figure can be obtained.

When the preceding state is “0”, “11101000” is allocated to the preamble“B”, “11100010” is allocated to the preamble “M”, and “1100100” isallocated to the preamble “W”. On the other hand, when the precedingstate is “1”, “00010111” is allocated to the preamble “B”, “00011101” isallocated to the preamble “M”, and “00011011” is allocated to thepreamble “W”.

FIG. 14 schematically shows a channel status format in the IEC 60958standard. The channel status is obtained by accumulating the 30th timeslot in the sub-frame for each block. In the figure, contents of thechannel status are arranged 1 byte each in the longitudinal direction,and a bit configuration in each byte is shown in the lateral direction.It should be noted that here, descriptions will be given while assuminga consumer use (Consumer use) format.

In a 0 byte, a 0 bit (bit 0) is a bit that indicates that the channelstatus is for a consumer use. A 1st bit (bit 1) is a bit that indicateswhether it is a linear PCM sample. 6th and 7th bits (bit 6-7) are afield indicating a mode of the channel status.

In a 3rd byte, 0 to 3rd bits (bit 24-27) and 6th and 7th bits (bit30-31) are each a field indicating a sampling frequency. FIG. 15 shows acurrent specified state. In the field, there is a reserved area so thata new sampling frequency can be specified as shown in the figure.

Transmission of SPDIF signals including 2-channel audio data is carriedout while conforming to the IEC 60958 standard. On the other hand,transmission of SPDIF signals including multichannel audio data (linearPCM) of 5.1 channels, 7.1 channels, 10.2 channels, 22.2 channels, andthe like becomes possible by extending the IEC 60958 standard.

The transmission of SPDIF signals including multichannel audio data(linear PCM) will be described. The IEC 60958 standard is in wide use,and the transmission side may start transmission without checkingperformance on the reception side. Therefore, there is a need to notcause a failure in such a case or even when data in a new format istransmitted to a receiver that has been commercialized in the past. Atthe very least, there is a need for the receiver to not cause noises.5.1 is widely used as the number of channels for multichannel audio, and7.1, 10.2, and 22.2 channels are also expected to be used and to prevailin future broadcasts.

As means for not influencing receivers of the past, there is a use of atransmission frequency that is not currently used. As the transmissionfrequency, a transmission frequency that is 4 times the samplingfrequency specified in the IEC 60958 standard is used. This is foradding auxiliary information, assigning preambles, and carrying outbiphase mark modulation on the audio data to be transmitted.

For example, when transmitting 5.1-channel audio data, a 6-channeltransmission band only needs to be secured, and a transmission frequencythat is 3 times that used in the normal transmission, that is, 2-channeltransmission, only needs to be used. For example, when the samplingfrequency per channel is 48 kHz, 144 kHz (=48 kHz*3) is newly defined asthe sampling frequency, and “Bit 24-27”=“1110b” and “Bit 30-31”=“00b”,for example, are assigned to the reserved areas of “bit 24-27” and “bit30-31” of the channel status (see FIG. 14).

Further, for example, when transmitting 10.2-channel audio data, a12-channel transmission band only needs to be secured, and atransmission frequency that is 6 times that used in the normaltransmission, that is, 2-channel transmission, only needs to be used.For example, when the sampling frequency per channel is 48 kHz, 288 kHz(=48 kHz*6) is newly defined as the sampling frequency, and “Bit 24-27”=“1110b” and “Bit 30-31”=“01b”, for example, are assigned to thereserved areas of “bit 24-27” and “bit 30-31” of the channel status (seeFIG. 14). It should be noted that when transmitting 7.1-channel audiodata, a 12-channel transmission band secured as described above is used,for example.

Further, for example, when transmitting 22.2-channel audio data, a24-channel transmission band only needs to be secured, and atransmission frequency that is 12 times that used in the normaltransmission, that is, 2-channel transmission, only needs to be used.For example, when the sampling frequency per channel is 48 kHz, 576 kHz(=48 kHz*12) is newly defined as the sampling frequency, and “Bit24-27”=“1110b” and “Bit 30-31”=“10b”, for example, are assigned to thereserved areas of “bit 24-27” and “bit 30-31” of the channel status (seeFIG. 14).

FIG. 16(a) shows a correspondence relationship between the number ofchannels and the sampling frequency in a case where the samplingfrequency per channel is 48 kHz. It should be noted that althoughdescriptions will be omitted, also when the sampling frequency perchannel is a frequency other than 48 kHz, that is, 44.1 kHz or 32 kHz,for example, sampling frequencies corresponding to the number ofchannels of 6, 12, and 24 can be newly defined in a similar manner. Bynewly defining the sampling frequency as described above, pieces ofaudio data of the respective channels that configure the multichannelaudio data included in the SPDIF signals are given a dedicated samplingfrequency corresponding to the number of channels. In other words, thenumber of channels can be recognized by the sampling frequency.

It should be noted that the actual transmission frequency becomes 4times the sampling frequency as described above. For example, in thecase of 6 channels, the transmission frequency becomes 576 kHz (=144kHz*4). Moreover, as the bit assign method, there is a method of givinga meaning of a pointer of being designated in other areas to “Bit24-27”=“1110b” and “Bit 30-31”=“00b” as shown in FIG. 16(b) and writinga value in the area of “Bit 61-66” for identification, for example, inaddition to the method shown in FIG. 16(a). By the method shown in FIG.16(b), a usage of the reserved area of “Bit 30-31” can be suppressed.

The receiver of the past (receiver of related art) does not know acombination of values to be newly assigned to the areas of “bit 24-27”and “bit 30-31” of the channel status as described above. Further, sincethe transmission frequency (e.g., 576 kHz in case of 6 channels) is new,in the receiver of the past, a PLL is not locked, data cannot be readand an error is eventually caused, audio is muted, and noises are notoutput. The specified sampling frequency is selected to be an evenmultiple of 32 kHz, 44.1 kHz, and 48 kHz. If the transmission frequencyis an even multiple of these frequencies, there is a possibility thatthe PLL will be locked (including pseudo lock). However, by selecting afrequency that is an even multiple of 3 times these frequencies as thetransmission frequency as described above, it becomes possible to avoidthe PLL of the receiver of the past from being erroneously locked.

When transmitting SPDIF signals including multichannel audio data(linear PCM), the transmission band can be secured by defining thesampling frequency as described above, but there is still a need tospecify where the multi-channels start. Since 2-channel transmission hasbeen used in the IEC 60958 standard, 3 types of preambles B, M, and Whave been detected to identify Channels 1 and 2.

Here, also in the case of multichannel transmission of N channels (6channels, 12 channels, and 24 channels), by setting the channel numberso as to start from the preamble B, assigning Channel 1, Channel 2,Channel 3, . . . , and Channel N, and assigning them so that the channelstarts from Channel 1 again, the channel number identification on thereception side becomes possible.

Further, although one block is constituted of 192 frames in the IEC60958 standard, since 192 is an integral multiple in any of 6 channels,12 channels, and 24 channels, repetitions thereof do not cause anydiscrepancies. FIG. 17 shows an example of a frame configuration of themultichannel transmission using 6 channels.

A 6-channel cluster (6ch cluster) is configured every 3 frames.Specifically, 6-channel cluster 0 is configured in Frames 0 to 2,6-channel cluster 1 is configured in Frames 3 to 5, and repeats afterthat. Further, in this case, Channels 1 and 2 are assigned to Frame 0,Channels 3 and 4 are assigned to Frame 1, Channels 5 and 6 are assignedto Frame 2, and repeats after that. It should be noted that although notillustrated in the figure, the same holds true for the frameconfigurations in the multichannel transmissions of 12 channels and 24channels.

While the channel number identification becomes possible by the assignmethod described above in the case of the multichannel transmission,there is still a need to designate speaker positions to actuallyreproduce audio data of the respective channels. In other words,information on a correspondence relationship between the channels andthe speaker positions becomes necessary.

In this embodiment, areas for the information that indicates acorrespondence relationship between the channels and the speakerpositions are provided in the channel status (see FIG. 14). Accordingly,it becomes possible to designate positions of speakers to reproduceaudio data of the respective channels in sync with the multichannelaudio data.

For example, as shown in FIG. 14, information that indicates thecorrespondence relationship between the channels and the speakerpositions is inserted in the area of “bit 67-74” in the channel status.By using this 8-bit area, 255 combinations of speaker positions can bedesignated. It should be noted that all-0 is not used in considerationof past compatibility.

FIG. 18 shows an example of values of “bit 67-74” and a correspondencerelationship between the channels respectively indicated by those valuesand the speaker positions. Here, FL, FR, FC, and the like that indicatethe speaker positions can be used to identify a maximum of 32 channelsby referencing the IEC 60958 standard. Although only up to 24 channelsare referred to in the specification, a method of identifying up to 32channels is exemplified considering extensions in the future. In theexample shown in the figure, “-” indicates that while data exists in adata slot, there is no valid data, and the data will not be used foraudio reproduction.

Based on the information indicating the correspondence relationshipbetween the channels and the speaker positions, the reception side cansupply the audio data of the respective channels to the correspondingspeakers. Moreover, based on this information, the reception side canalso display what kind of multichannel audio has been transmitted on thedisplay panel for the user to see.

FIGS. 19 each show an example of UI display on the reception side. FIG.19(a) shows display in a case where a 2-channel transmission isperformed, and FIG. 19(b) shows display in a case where the transmissionis switched to 5.1 channels, that is, a 6-channel transmission. Althoughnot shown in the figure, similar display is performed also in the caseof other multichannel transmissions. In the AV system 10 shown in FIG.1, the reception side is the audio amplifier 200, and UI display isperformed on the display panel 217 (see FIG. 3). It should be noted thatsimilar UI display can also be performed on the transmission side. Inthe AV system 10 shown in FIG. 1, the transmission side is thetelevision receiver 100, and UI display is performed on the displaypanel 111 (see FIG. 2).

Further, by providing an area for specifying support information of anew sampling frequency or providing a new descriptor in an audio shortdescriptor (Audio Short Descriptor) specified in CEA-861, it becomespossible to present performance of the reception side to thetransmission side and improve connectivity.

FIG. 20(a) shows a configuration example of the current audio shortdescriptor (Audio Short Descriptor). FIG. 20(b) shows a configurationexample of the audio short descriptor in which areas for specifyingsupport information of new sampling frequencies (576 kHz, 288 kHz, 144kHz) are newly defined. FIG. 20(c) shows a configuration example of anewly-created multichannel-dedicated descriptor in which areas forspecifying support information of new sampling frequencies (576 kHz, 288kHz, 144 kHz) are provided.

FIG. 21 is a flowchart showing an operational example of the televisionreceiver 100 as the SPDIF signal transmission side. This example is anexample that handles 6-channel (5.1-channel) audio data. In Step ST1,the television receiver 100 acquires 6-channel (5.1-channel) audio dataand prepares for output.

Next, in Step ST2, the television receiver 100 acquires information onthe audio short descriptor of the audio amplifier 200 as the receptionside. For example, the television receiver 100 is capable of acquiringthe information by communicating with the audio amplifier 200 using theCEC line. In Step ST3, the television receiver 100 determines whether144 kHz is supported as the sampling frequency on the reception side.

When determined as being supported, the television receiver 100generates SPDIF signals including 6-channel audio data having a samplingfrequency of 144 kHz and transmits the signals to the audio amplifier200 as the reception side in Step ST4. When determined as not beingsupported, the television receiver 100 proceeds to processing of StepST5.

In Step ST5, the television receiver 100 carries out processing ofdownmixing from 6 channels to 2 channels and acquires 2-channel audiodata. Then, in Step ST6, the television receiver 100 generates SPDIFsignals including 2-channel audio data having a sampling frequency of 48kHz and transmits the signals to the audio amplifier 200 as thereception side.

It should be noted that in the operational example shown in theflowchart of FIG. 21, if the reception side supports 144 kHz, thetelevision receiver 100 immediately performs a 6-channel (5.1-channel)output. In this case, however, a 2-channel output is also possible bycarrying out the downmix processing. In this regard, in this case, it isalso possible to UI-display output mode options so as to prompt the userto select a desired output mode.

FIG. 22(a) shows an example of the UI display in such a case. When theuser selects a 6-channel (5.1-channel) output mode, the UI displaychanges to that shown in FIG. 22(b), and the user can confirm theselection of the output mode.

[Details of encryption]

As shown in FIG. 23, in the SPDIF transmission circuit 104 of thetelevision receiver 100, SPDIF signals including linear PCM audio dataof the respective channels are generated using input 2-channel ormultichannel audio data SA. At this time, the encryption unit 104 acarries out encryption processing on the audio data of the respectivechannels. Here, referring to the sub-frame configuration shown in FIG.11, only the audio data (Audio sample word) portion or a portion inwhich additional information is added to the audio data is encrypted.Which processing is to be selected depends on the encryption scheme.

The SPDIF signals generated by the SPDIF transmission circuit 104 aretransmitted to the SPDIF reception circuit 204 of the audio amplifier200 via an HDMI ARC (HDMI Audio Return Channel) constituted of a pair oflines including the reserve line and the HPD line of the HDMI cable asdescribed above. The SPDIF reception circuit 204 receives the SPDIFsignals and obtains the audio data of the respective channels. At thistime, the decoding unit 204 a carries out decode processing on the audiodata of the respective channels.

Here, the CPU 121 of the television receiver 100 and the CPU 212 of theaudio amplifier 200 performs apparatus authentication and key exchangeusing the bidirectional communication channel different from the HDMIARC. For example, CEC, DDC, or the like can be used as the bidirectionalcommunication channel.

The SPDIF transmission circuit 104 adds encrypted-state informationindicating encryption of data to the audio data included in the SPDIFsignals. For example, the SPDIF transmission circuit 104 adds theencrypted-state information using a predetermined bit area of thechannel status (see FIG. 14). In this case, for example, the encryptedstate is indicated by setting a value of the predetermined 1-bit area ofthe channel status such that “0” and “1” are repeated alternately foreach block.

In this embodiment, an area of “Byte0 Bit1” of the channel status isused as the predetermined 1-bit area. This 1-bit area is defined suchthat “0” indicates a linear PCM transmission and “1” indicates othertransmissions in the IEC 60958 standard. In the case of “1”, forexample, IEC 61937 as a compressed audio data transmission is used.

In this embodiment, the encryption transmission is enabled by assigningthe state where “0” and “1” are alternately repeated for each block tothe status of encrypted. Since “0” becomes consecutive in the currentlinear PCM transmission and “1” becomes consecutive in the IEC 61937transmission, the state of alternately repeating “0” and “1” is new andthus can be distinguished from those transmissions. FIG. 24 shows astate where “Byte0 Bit1” is set to “0”. FIG. 25 shows a state where“Byte0 Bit1” is set to “1”.

Further, when a plurality of encryption schemes are assumed, forexample, the SPDIF transmission circuit 104 adds encryption schemeinformation indicating the encryption scheme to the audio data includedin the SPDIF signals. For example, the SPDIF transmission circuit 104inserts the encryption scheme information in a predetermined bit area,for example, the area of “bit 75-77”, of the channel status (see FIGS.24 and 25). By the encryption scheme information, the encryption schemecan be confirmed on the reception side, and appropriate decodeprocessing can be carried out.

The operations on the transmission side and the reception side that arecarried out when transmitting SPDIF signals will be described withreference to the sequence diagram shown in FIG. 26. (1) The transmissionside and the reception side perform apparatus authentication and keyexchange using a bidirectional communication channel different from anIEC 60958 transmission channel (HDMI ARC), such as CEC and DDC. (2)Next, the transmission side transmits unencrypted silent data to the IEC60958 transmission channel in a state where “Byte0 Bit1” is “0”.

Next, the transmission side encrypts audio data, sets a value of “Byte0Bit1” to “1” at a timing in sync with the encryption, and transmits itto the IEC 60958 transmission channel. After that, the transmission sidecarries out processing of alternately repeating “1” and “0” for eachblock. FIG. 27 shows a transition of the value of “Byte0 Bit1”.

(4) After the apparatus authentication and key exchange with thetransmission side, the reception side monitors the value of “Byte0Bit1”. (5) At a timing the value changes from “0” to “1”, the receptionside starts decoding and outputs reproduction data. (6) When detecting atransmission error, the reception side is muted. This transmission errorcan be detected by “Parity Bit” (see FIG. 11). (7) After that, thetransmission side and the reception side perform apparatusauthentication and key exchange again and repeats the operationsdescribed above.

As described above, in the AV system 10 shown in FIG. 1, audio dataincluded in the SPDIF signals transmitted from the television receiver100 to the audio amplifier 200 is encrypted, and encrypted-stateinformation indicating the data encryption is added to the audio data.Therefore, a high-level copyright protection of transmission audio databecomes possible, and the reception side can easily recognize that theaudio data has been encrypted.

Further, in the AV system 10 shown in FIG. 1, encryption schemeinformation indicating an encryption scheme is added to the audio dataincluded in the SPDIF signals transmitted from the television receiver100 to the audio amplifier 200. Therefore, the reception side can easilyrecognize what kind of encryption scheme the audio data has beenencrypted by, and thus decode processing can be carried outappropriately.

2. Modified Examples

In the embodiment above, the multichannel audio data included in theSPDIF signals are given a dedicated sampling frequency corresponding tothe number of channels, and the reception side can recognize the numberof channels by the dedicated sampling frequency. However, there may alsobe a method of defining preambles of a new bit string and changing apreamble sequence so as to enable the number of channels to berecognized.

FIG. 28 shows an example of preambles to be newly defined. A pattern ofeach preamble is a pattern not having a DC component (number of 0 andnumber of 1 are the same). For example, the pattern of the preamble “New1” is “11011000” when the preceding state is “0” and is “00100111” whenthe preceding state is “1”.

Further, for example, the pattern of the preamble “New 2” is “11011010”when the preceding state is “0” and is “00100101” when the precedingstate is “1”. Further, for example, the pattern of the preamble “New 3”is “11011100” when the preceding state is “0” and is “00101011” when thepreceding state is “1”.

FIG. 29 shows an example of a frame configuration in the 6-channelmultichannel transmission in a case where preambles to be newly definedare used as the preambles in place of the preambles “B”, “M”, and “W”.

A 6-channel cluster (6ch cluster) is configured every 3 frames.Specifically, 6-channel cluster 0 is configured in Frames 0 to 2,6-channel cluster 1 is configured in Frames 3 to 5, and repeats afterthat. In this case, Channels 1 and 2 are assigned to Frame 0, Channels 3and 4 are assigned to Frame 1, Channels 5 and 6 are assigned to Frame 2,and repeats after that.

In the first Channel 1 of the block, a preamble “New 1” is used, and“New 2” and “New 3” are alternately used for subsequent channels. Inthis case, the fact that the number of channels is 6 can be easilyrecognized by the preamble sequence. In this case, cluster boundariescan be identified by successively counting the channels from the startof the block, and thus 6-channel clusters each constituted of Channels 1to 6 can be grasped. It should be noted that although not shown in thefigure, it is possible to recognize the number of channels on thereception side by similarly changing the preamble sequence regarding theframe configuration in multichannel transmissions of 12 channels and 24channels.

Further, although not shown in the figure, it is also possible toadditionally define “New 4” and use the preamble “New 4” for the firstChannel 1 of each of the 6-channel clusters while excluding the firstChannel 1 of the block. In this case, the preamble “New 1” or “New 4” isused for Channel 1 at the head of each 6-channel cluster. Therefore, thereception side can identify the cluster boundaries by the preamble “New1” or “New 4” and easily grasp the 6-channel clusters each constitutedof Channels 1 to 6.

Since receivers of the past (receiver of related art) are incapable ofdetecting newly-defined preambles, audio reproduction is muted, and afailure in which noises are output or the like does not occur. It shouldbe noted that it is also possible to follow the existing way regardingfirst Channels 1 and 2 and assign newly-defined preambles to only thesubsequent channels for identification. FIG. 30 shows an example of theframe configuration in the multichannel transmission of 6 channels inthis case.

In this case, the preamble “B” or “M” (“B” is used only at head ofblock) is used in Channel 1, the preamble “W” is used in Channel 2, thepreamble “New 3” is used in Channel 3, the preamble “New 2” is used inChannel 4, the preamble “New 3” is used in Channel 5, and the preamble“New 2” is used in Channel 6. In this case, the preamble “B” or “M” isused for Channel 1 at the head of each of the 6-channel clusters.Therefore, the reception side can easily grasp the 6-channel clusterseach constituted of Channels 1 to 6.

When enabling the reception side to recognize the number of channels bychanging the preamble sequence as described above, there is no need touse a dedicated sampling frequency corresponding to the number ofchannels. In other words, multichannel audio data transmissions can alsobe performed using the sampling frequency defined in the past. Forexample, while 176.4 kHz is used as the sampling frequency, amultichannel transmission of 8 channels instead of 2 channels alsobecomes possible.

Further, the embodiment above has shown the example of using the HDMIARC for transmitting SPDIF signals from the television receiver 100 tothe audio amplifier 200, that is, the example where the HDMI ARC is usedas the IEC 60958 transmission channel. The present technology issimilarly applicable to an example where a coaxial cable or an opticalcable is used as the IEC 60958 transmission channel.

FIG. 31 shows a configuration example of an AV system 10A in a casewhere an optical cable is used as the IEC 60958 transmission channel. InFIG. 31, parts corresponding to those of FIG. 1 are denoted by the samesymbols, and detailed descriptions thereof will be omitted. In the AVsystem 10A, the television receiver 100 includes an optical interface129, and the audio amplifier 200 includes an optical interface 222. Inaddition, SPDIF signals output from the SPDIF transmission circuit 104of the television receiver 100 are transmitted to the SPDIF receptioncircuit 204 of the audio amplifier 200 via the optical interface 129, anoptical cable 630, and the optical interface 222.

It should be noted that the example of using the HDMI ARC as the IEC60958 transmission channel (see FIG. 1) and the example of using acoaxial cable or optical cable as the IEC 60958 transmission channel(see FIG. 31) have been described above.

In addition, an example of using an HDMI transmission channel as the IEC60958 transmission channel as shown in FIG. 32(a) is also possible. Inthis case, SPDIF signals (IEC 60958 signals) are mapped to an audiosample packet (audio sample packet) and transmitted in the same forwarddirection as a video transmission. An audio short descriptor (Audioshort descriptor) in the HDMI receiver is read by the HDMI transmittervia a DDC line in the HDMI transmission channel. Similarly, an exampleof using a display port transmission channel (DP transmission channel)as the IEC 60958 transmission channel as shown in FIG. 32(b) is alsopossible. Also in this case, SPDIF signals (IEC 60958 signals) aremapped to an audio sample packet (audio sample packet) and transmittedin the same forward direction as the video transmission.

Furthermore, the present technology may also take the followingconfigurations.

(1) A transmission apparatus, including:

-   -   a data transmission unit that sequentially transmits audio data        to a reception side via a predetermined transmission channel for        each unit audio data;    -   an encryption unit that encrypts the audio data transmitted by        the data transmission unit; and    -   an information addition unit that adds, to the audio data        transmitted by the data transmission unit, encrypted-state        information indicating that the audio data has been encrypted.        (2) The transmission apparatus according to (1), in which    -   the information addition unit adds the encrypted-state        information using a predetermined bit area of a channel status        of each block that is configured every predetermined number of        unit audio data pieces.        (3) The transmission apparatus according to (2), in which    -   the information addition unit indicates the encrypted state by        alternately and repetitively setting, for the respective blocks,        “0” and “1” as a value of a predetermined 1-bit area of the        channel status of each block.        (4) The transmission apparatus according to (3), in which    -   the predetermined 1-bit area is an area that indicates whether        the audio data transmitted by the data transmission unit is        linear PCM.        (5) The transmission apparatus according to any one of (1) to        (4), in which    -   the information addition unit further adds, to the audio data        transmitted by the data transmission unit, encryption scheme        information that indicates an encryption scheme for the        encryption.        (6) The transmission apparatus according to (5), in which    -   the information addition unit adds the encryption scheme        information using a predetermined bit area of a channel status        of each block that is configured every predetermined number of        unit audio data pieces.        (7) The transmission apparatus according to any one of (1) to        (6), in which    -   the audio data is multichannel audio data of a predetermined        number of channels, and    -   the data transmission unit sequentially transmits audio data of        the respective channels configuring the multichannel audio data        to the reception side via the predetermined transmission channel        for each unit audio data.        (8) The transmission apparatus according to (7), in which    -   the predetermined number of channels is 6, 12, or 24.        (9) A transmission method, including the steps of:    -   sequentially transmitting, by a data transmission unit, audio        data to a reception side via a predetermined transmission        channel for each unit audio data;    -   encrypting audio data transmitted in the data transmission step;        and    -   adding, to the audio data transmitted in the data transmission        step, encrypted-state information indicating that the audio data        has been encrypted.        (10) A reception apparatus, including:    -   a data reception unit that sequentially receives audio data        transmitted from a transmission side via a predetermined        transmission channel for each unit audio data,    -   the audio data received by the data reception unit being        encrypted,    -   the audio data received by the data reception unit having        encrypted-state information indicating that the audio data has        been encrypted added thereto; and    -   a decoding unit that carries out decode processing on the audio        data received by the data reception unit based on the        encrypted-state information.        (11) The reception apparatus according to (10), in which    -   the encrypted-state information is added to the audio data        received by the data reception unit using a predetermined bit        area of a channel status of each block that is configured every        predetermined number of unit audio data pieces.        (12) The reception apparatus according to (11), in which    -   the encrypted state is indicated by alternately and repetitively        setting, for the respective blocks, “0” and “1” as a value of a        predetermined 1-bit area of the channel status of each block.        (13) The reception apparatus according to (12), in which    -   the predetermined 1-bit area is an area that indicates whether        the audio data received by the data reception unit is linear        PCM.        (14) The reception apparatus according to any one of (10) to        (13), in which    -   the audio data received by the data reception unit further has        encryption scheme information that indicates an encryption        scheme for the encryption added thereto, and    -   the decoding unit carries out, on the audio data received by the        data reception unit, decode processing corresponding to the        encryption scheme indicated by the encryption scheme        information.        (15) The reception apparatus according to (14), in which    -   the encryption scheme information is added to the audio data        received by the data reception unit using a predetermined bit        area of a channel status of each block that is configured every        predetermined number of unit audio data pieces.        (16) The reception apparatus according to any one of (10) to        (15), in which    -   the audio data is multichannel audio data of a predetermined        number of channels, and    -   the data reception unit sequentially receives audio data of the        respective channels configuring the multichannel audio data from        the transmission side via the predetermined transmission channel        for each unit audio data.        (17) The reception apparatus according to (16), in which    -   the predetermined number of channels is 6, 12, or 24.        (18) A reception method, including the steps of:    -   sequentially receiving, by a data reception unit, audio data        transmitted from a transmission side via a predetermined        transmission channel for each unit audio data,        -   the audio data received in the data reception step being            encrypted,        -   the audio data received in the data reception step having            encrypted-state information indicating that the audio data            has been encrypted added thereto; and    -   carrying out decode processing on the audio data received in the        data reception step based on the encrypted-state information.

REFERENCE SIGNS LIST

-   10 AV system-   100 television receiver-   101 HDMI terminal-   102 HDMI reception unit-   103 high-speed bus interface-   104 SPDIF transmission circuit-   104 a encryption unit-   105 antenna terminal-   106 digital tuner-   107 MPEG decoder-   108 video signal processing circuit-   109 graphic generation circuit-   110 panel drive circuit-   111 display panel-   112 audio signal processing circuit-   113 audio amplification circuit-   114 speaker-   115 Ethernet interface-   116 network terminal-   120 internal bus-   121 CPU-   122 flash ROM-   123 DRAM-   124 display control unit-   125 remote control reception unit-   126 remote control transmitter-   127 power supply unit-   128 plug connection transmission circuit-   200 audio amplifier-   201 a, 201 b HDMI terminal-   202 a HDMI transmission unit-   202 b HDMI reception unit-   203 a, 203 b high-speed bus interface-   204 SPDIF reception circuit-   204 a decoding unit-   205 MPEG decoder-   206 video/graphic processing circuit-   207 audio processing circuit-   208 audio amplification circuit-   209 audio output terminal-   210 Ethernet interface-   211 internal bus-   212 CPU-   213 flash ROM-   214 DRAM-   215 display control unit-   216 panel drive circuit-   217 display panel-   218 power supply unit-   219 remote control reception unit-   220 remote control transmitter-   221 plug connection detection circuit-   300 BD player-   301 HDMI terminal-   302 HDMI transmission unit-   303 high-speed bus interface-   304 internal bus-   305 CPU-   306 flash ROM-   307 SDRAM-   308 display control unit-   309 remote control reception unit-   310 remote control transmitter-   311 storage medium control interface-   312 a BD drive-   312 b HDD-   312 c SDD-   313 Ethernet interface-   314 network terminal-   315 MPEG decoder-   316 graphic generation circuit-   317 video output terminal-   318 audio output terminal-   319 panel drive circuit-   320 display panel-   321 power supply unit-   400 reception antenna-   500 speaker system-   610, 620 HDMI cable-   630 optical cable

1. A transmission apparatus, comprising: a data transmission unit thatsequentially transmits audio data to a reception side via apredetermined transmission channel for each unit audio data; anencryption unit that encrypts the audio data transmitted by the datatransmission unit; and an information addition unit that adds, to theaudio data transmitted by the data transmission unit, encrypted-stateinformation indicating that the audio data has been encrypted.
 2. Thetransmission apparatus according to claim 1, wherein the informationaddition unit adds the encrypted-state information using a predeterminedbit area of a channel status of each block that is configured everypredetermined number of unit audio data pieces.
 3. The transmissionapparatus according to claim 2, wherein the information addition unitindicates the encrypted state by alternately and repetitively setting,for the respective blocks, “0” and “1” as a value of a predetermined1-bit area of the channel status of each block.
 4. The transmissionapparatus according to claim 3, wherein the predetermined 1-bit area isan area that indicates whether the audio data transmitted by the datatransmission unit is linear PCM.
 5. The transmission apparatus accordingto claim 1, wherein the information addition unit further adds, to theaudio data transmitted by the data transmission unit, encryption schemeinformation that indicates an encryption scheme for the encryption. 6.The transmission apparatus according to claim 5, wherein the informationaddition unit adds the encryption scheme information using apredetermined bit area of a channel status of each block that isconfigured every predetermined number of unit audio data pieces.
 7. Thetransmission apparatus according to claim 1, wherein the audio data ismultichannel audio data of a predetermined number of channels, and thedata transmission unit sequentially transmits audio data of therespective channels configuring the multichannel audio data to thereception side via the predetermined transmission channel for each unitaudio data.
 8. The transmission apparatus according to claim 7, whereinthe predetermined number of channels is 6, 12, or
 24. 9. A transmissionmethod, comprising the steps of: sequentially transmitting, by a datatransmission unit, audio data to a reception side via a predeterminedtransmission channel for each unit audio data; encrypting audio datatransmitted in the data transmission step; and adding, to the audio datatransmitted in the data transmission step, encrypted-state informationindicating that the audio data has been encrypted.
 10. A receptionapparatus, comprising: a data reception unit that sequentially receivesaudio data transmitted from a transmission side via a predeterminedtransmission channel for each unit audio data, the audio data receivedby the data reception unit being encrypted, the audio data received bythe data reception unit having encrypted-state information indicatingthat the audio data has been encrypted added thereto; and a decodingunit that carries out decode processing on the audio data received bythe data reception unit based on the encrypted-state information. 11.The reception apparatus according to claim 10, wherein theencrypted-state information is added to the audio data received by thedata reception unit using a predetermined bit area of a channel statusof each block that is configured every predetermined number of unitaudio data pieces.
 12. The reception apparatus according to claim 11,wherein the encrypted state is indicated by alternately and repetitivelysetting, for the respective blocks, “0” and “1” as a value of apredetermined 1-bit area of the channel status of each block.
 13. Thereception apparatus according to claim 12, wherein the predetermined1-bit area is an area that indicates whether the audio data received bythe data reception unit is linear PCM.
 14. The reception apparatusaccording to claim 10, wherein the audio data received by the datareception unit further has encryption scheme information that indicatesan encryption scheme for the encryption added thereto, and the decodingunit carries out, on the audio data received by the data reception unit,decode processing corresponding to the encryption scheme indicated bythe encryption scheme information.
 15. The reception apparatus accordingto claim 14, wherein the encryption scheme information is added to theaudio data received by the data reception unit using a predetermined bitarea of a channel status of each block that is configured everypredetermined number of unit audio data pieces.
 16. The receptionapparatus according to claim 10, wherein the audio data is multichannelaudio data of a predetermined number of channels, and the data receptionunit sequentially receives audio data of the respective channelsconfiguring the multichannel audio data from the transmission side viathe predetermined transmission channel for each unit audio data.
 17. Thereception apparatus according to claim 16, wherein the predeterminednumber of channels is 6, 12, or
 24. 18. A reception method, comprisingthe steps of: sequentially receiving, by a data reception unit, audiodata transmitted from a transmission side via a predeterminedtransmission channel for each unit audio data, the audio data receivedin the data reception step being encrypted, the audio data received inthe data reception step having encrypted-state information indicatingthat the audio data has been encrypted added thereto; and carrying outdecode processing on the audio data received in the data reception stepbased on the encrypted-state information.